The present invention relates generally to the gloss inherent in the hardcopy of image data be it pictorial or text. More particularly, this invention relates to halftoned image data and the control of differential gloss when that halftone image data is printed into hardcopy.
It is desirable to have a way to protect against the copying of a document. Most desirably in a manner that part of the content can be readily observed by a human reader but not by a copier scanner. One approach is where an image is printed using clear toner or ink, creating a difference in reflected light and diffused light that can be discerned by a human reader by holding the paper at an angle, but can not be detected by a copier scanner which is restricted to reading at right angles to the page.
There has been a need for a printer that can print a page that can be read but not copied. One method, described in U.S. Pat. Nos. 4,210,346 and 5,695,220 is to use a particular white toner and a particular white paper that are designed to have different diffused light characteristics at different angles. Of course, this system requires special, matched paper and toner.
In U.S. Pat. No. 6,108,512 to Hanna, the invention described discloses a system for producing non-copyable prints. In a xerographic printer, text is printed using clear toner. Thus, the only optical difference between toner and non-toner portions of the page is in the reflectivity. The plastic toner will reflect more light than the paper. A human reader can now read the image by holding the page at such an angle that the eye will intercept the reflected light from the toner, producing a contrast between the lighter appearing toner and the darker appearing paper. However, a copier scanner is always set up to avoid reflected light, by supplying light at an oblique angle and reading at a right angle. In this case, the diffused light is approximately equal for both toned and untoned surfaces, the scanner will detect no difference and the copier will not be able to copy the original.
Another approach taken to provide a document for which copy control is provided includes digital watermarking. As an example in U.S. Pat. No. 5,734,752 to Knox, there is disclosed a method for generating watermarks in a digitally reproducible document which are substantially invisible when viewed including the steps of: (1) producing a first stochastic screen pattern suitable for reproducing a gray image on a document; (2) deriving at least one stochastic screen description that is related to said first pattern; (3) producing a document containing the first stochastic screen; (4) producing a second document containing one or more of the stochastic screens in combination, whereby upon placing the first and second document in superposition relationship to allow viewing of both documents together, correlation between the first stochastic pattern on each document occurs everywhere within the documents where the first screen is used, and correlation does not occur where the area where the derived stochastic screens occur and the image placed therein using the derived stochastic screens becomes visible.
All of the above are herein incorporated by reference in their entirety for their teaching.
A further problem extant the teachings provided in U.S. Pat. No. 7,180,635 entitled “HALFTONE IMAGE GLOSS CONTROL FOR GLOSSMARKS” and incorporated above, is that the rendering of a desired glossmark image is most effective in halftone regions of the print of a primary image where the halftone structures in the primary image can be changed significantly without visual density/color change. In solid coverage (100%) and highlight (low density) regions, the manipulable gloss differential is weak or near zero.
Therefore, as discussed above, there exists a need for an arrangement and methodology which will control gloss and allow manipulation for glossmark hardcopy while improving and expanding the range of workable densities over which the glossmark image technique will be effective for a given primary image. Included in this need is the desirability of generating an image which may not be readily copied yet is readily discernable as such to the unaided observer. Thus, it would be desirable to solve this and other deficiencies and disadvantages as discussed above, with an improved methodology for the manipulation of inherent gloss.
The present invention relates to a method for the manipulation of the differential gloss as may be inherent in a halftone image comprising the steps of selecting a first halftone having a first anisotropic structure orientation, and then selecting a second halftone having a second anisotropic structure orientation different from the first halftone. The first halftone being applied to at least one portion of the halftone image, and the second halftone being applied to the remaining portions of the halftone image. This is followed by applying a clear toner to some portion of a hardcopy output of the halftone image resulting from the above steps.
In particular, the present invention relates to a method for the manipulation of the perceived gloss in a halftone image comprising the steps of selecting a first halftone having an anisotropic structure orientation, selecting a second halftone having a second anisotropic structure orientation different from the first halftone, applying the first halftone to at least some portion of the halftone image, and applying the second halftone to the remaining portion of the halftone image. The method also comprises applying a low density pattern of a light color to all low density areas in the halftone image.
The present invention also relates to a method for the manipulation of the perceived gloss in a halftone image comprising the steps of selecting a first halftone having a first anisotropic structure orientation, selecting a second halftone having a second anisotropic structure orientation different from that of the first halftone. The steps which follow entail applying the first halftone to at least some portion of the halftone image, applying the second halftone to another portion of the halftone image, and applying an under-color to all high density areas in the halftone image.